The present application relates to communication techniques, and more particularly, but not exclusively, relates to techniques to determine which devices among a population of distributed wireless communication devices are within a communication range of a particular device. These techniques find application in Mobile Ad hoc Networks (MANETs), nonmobile networks, and other communication systems.
In a typical wireless network, each node is given one or more unique physical addresses to identify its network interface(s). An example is a peer-to-peer network which uses MAC addresses to identify nodes in the network. In order to send data across a wireless network, each communicating party acquires the network interface addresses of its communicating peers in its neighborhood, with which the node has a direct link.
Neighborhood discovery by nodes in ad hoc networks often makes use of random access techniques. In one scheme, a query node sends a beacon signal and each node in the neighborhood transmits a frame which contains its network interface address after a random delay. A random delay is used to avoid collision of transmissions of neighboring nodes. Still, collisions occur because coordination is generally not possible before each node determines its neighborhood. Thus several retransmissions after random delays are typically used in wireless networks. As a result, it often takes a fairly large total delay to guarantee accurate enough discovery. Such random access neighbor discovery protocols have been specified for the ad hoc mode of IEEE 802.11 standards as well as for generic mobile ad hoc networks by the IETF MANET working group. Various extensions of the basic idea have been proposed, including the “birthday protocol,” which allows simultaneous discovery by all terminals of their respective neighborhoods, as well as schemes using directional antennas.
Even so, there remains a need for faster ways to perform neighbor discovery. Accordingly, further contributions are needed in this area of technology.